Future communication networks are getting more heterogeneous and more dense base station deployment will be used for handling increasing cellular network capacity needs.
Hence, handling seamless mobility between Access Nodes (ANs) will be one key issue in the future, where communication networks are becoming more and more user centric.
Also different types of new data transmission schemes are visualized for the future communication system. Users could for example be able to send small amounts of data without connection or with contention based manner during idle mode. These would require new user identification methods.
Currently, communication networks based on 3GPP standards use Cell Radio Network Temporary Identifier (C-RNTI) to identify a User Equipment (UE) connected to a cell. When handover procedure has been performed or Radio Resource Connection (RRC) connection is re-established, the UE needs to do Random Access (RA) procedure for getting a valid C-RNTI.
In Long Term Evolution (LTE) there also exist other RNTI types. This is also the case in Universal Mobile Telecommunications Systems (UMTS) where there are multiple RNTI types for different purposes, and some of them have different scopes. For example, the cell RNTI is valid in a cell, the S:RNTI is valid in the scope of the serving Radio Network Controller (RNC) and the User-RNTI (U-RNTI) is unique in the whole Universal Terrestrial Radio Access Network (UTRAN) since it consists of a random RNTI for the UE and serving RNC Identity (ID).
When the UE is in idle mode the UE is identified with a Temporary Mobile Subscriber Identity (TMSI), which is valid in a larger area but is only used for idle mode procedures such as paging of UEs and service request.